In many instances it is desirable for a multi-row planter to be capable of seed planting, fertilizing and the application of liquid herbicide in a single pass. Accordingly, some multi-row planters are provided with seed bins for containing seed to be planted, fertilizer boxes and herbicide tanks. However, the weight represented by a reasonable supply of liquid herbicide (as for example 500 gallons) cannot be carried on conventional planters. Thus, the volume of liquid herbicide which may be carried on conventional planters is severely limited and frequent stops are therefore required to replenish the supply of liquid herbicide and a tank vehicle of the desired capacity must be provided and operable over farm land in order to transport a continuing supply of liquid herbicide to a planter. Also, a planter equipped with reasonably small volume liquid herbicide tanks is limited, by the herbicide tanks, in its capacity to carry fertilizer. Accordingly, if liquid herbicide tanks can be omitted from a planter, larger fertilizer boxes may be carried on the planter.
In addition to liquid herbicide tanks being provided on planters, it is possible to mount liquid herbicide tanks on a tractor being utilized to tow a planter. However, if a reasonable supply of liquid herbicide is to be carried by a tractor, a larger heavy duty tractor is required to carry the additional weight represented by the liquid herbicide. Further, the mounting of liquid herbicide tanks on a tractor necessitate that the tanks be removed and reinstalled seasonally, limits the use of one planter to a single tractor, results interruption of the planting operation as a result of tractor breakdown, overloads the tractor and increases the tendency of the tractor to become stuck in soft ground and requires that a replenishing supply of liquid herbicide be hauled to the tractor.
Various forms of tank trailers have been heretofore designed and other types of trailers have included gooseneck towing tongues. Examples of several forms of tank trailers and other trailers equipped with gooseneck towing tongues are disclosed in U.S. Pat. Nos. 2,842,899, 3,295,482, 3,396,685, 3,698,740, 3,796,433 and 3,840,252.